Upholstery spring coil

ABSTRACT

A helical wire coil compression spring for upholstery use having a plurality of convolutions of pitch substantially greater than the thickness of the wire and terminating at one end in a wire portion extending as a chord across the end convolution.

United States Patent [191' Stnmpl 1 Nov. 12, 1974 UPHOLSTERY SPRING COILWalter Stumpf, Munster, lnd.

Simmons Company, New York. NY.

Filed: Jan. 18, 1972 App]. No.: 218,842

Related US. Application Data Continuation of Ser. Nov 829.533. June 2,abandoned.

lnventor:

Assignee:

US. Cl 267/91, 267/166, 267/180 Int. Cl. Fl6f 3/04 Field of Search267/91, 92, 166, 180

References Cited UNITED STATES PATENTS Eldridge 267/91 FOREIGN PATENTSOR APPLICATIONS 182,683 2/1963 Sweden 267/18 Primary E.raminer.lamcs B.Mttrbert Attorney, Agent, or Firm-Fitch. Even. Tubin & Luedekn [57ABSTRACT A helical wire coil compression spring for upholstery usehaving a plurality of convolutions of pitch substantially greater thanthe thickness of the wire and terminating at one end in a wire portionextending as a chord across the end convolution.

4 Claims, 13 Drawing Figures PATENTEDNUV 12 I974 FlG.l

INVENTOR WALTER STUNPF PATENTE U I974 sum 3m: 7 3,847,379

FIGAa 42 I02 30 32 I02 42 I56 INVENTOR WALTER STUNPF ATTYS.

PATENTEDnuv 12 I974 SHEU 0F 7 INVENTOR WALTER STUNPF PATENTED NOV 12I974 SHEET 8 0F 7 ATTYS This application is a continuation of my earlierapplication Ser. No. 829,533, filed June 2, 1969, (and now abandoned).

This invention relates to the manufacture of box springs, by which termI mean to include not only box springs as such, i.e., upholstered springconstructions mounted upon flat wooden frames and usually employed upona bedstead or bedframe as a foundation for a mattress, but also similarsuch upholstered constructions employed as bases of studio couches,upholstered sofas, upholstered chairs, and the like.

As disclosed in my aforementioned parent application Ser. No. 829,533,the invention contemplated (1) a method of assembly springs into aconstruction, i.e., the arrangement of individual coil springs into aseries of rows in regular pattern by virtue of the attachment of suchspring coils individually to a base frame of wood or the like by meansof stapling, that method having been divided from the parent applicationby requirement, and re-presented in co-pending application Ser. No.218,821, filed Jan. l8, 1972, now Pat. No. 3,789,495; (2) a specialapparatus for carrying out the method,the apparatus having also beendivided from the parent application by requirement, and represented inco-pending application Ser. No. 218,843 filed Jan. 18, 1972, now Pat.No. 3,770,180; and (3) the particular form of upholstery spring coilwhich is Y the subject of this application, and which is particularlyadapted to the practice of the method.

Since the days of the hand-tied box-spring construction, which onceconstituted a majority of those made, particularly those of higherquality, various attempts have been made to adapt the box spring formachine assembly without a great deal of success. Until recently,machine assembly of box springs has been limited to the use ofpre-assembled spring constructions of hour-glass coils such as are usedin mattresses, i.e., adjacent rows of springs united by helicaltie-wires, and the stapling of such assemblies or spring constructionsas a unit to a wooden slat frame. This technique is essentially limitedtothe double-cone or hour-glass type of coil,which has limitations bothfunctional and economic when used as a box spring, particularly for cer'tain kinds of mattresses that best serve their function when emplacedupon a relatively inflexible but resiliently-mounted platform.

Assembly of box spring constructions of the conecoil type, which ispreferred for many sleeping and sitting cushion-bases, has beenperformed essentially by hand, the spring coils being assembled by handmethods into an assembly or construction of suitable size, which is thensecured to a wooden slat frame by stapling. The process remainsexpensive because of the labor involved, and unless considerable care betaken, the construction can be noisy if the contacting metallic partsare not tightly interlocked.

While some attempts have heretofore been made toit is the primary objectof this invention, therefore, to improve the mechanized manufacture ofbox springs, this object being accomplished by a change in the characterof the cone coil, the provision of a stapling gun and technique adaptedto handle such a coil and to secure it to the slat frame with a singlestaple, and the provision of the necessary apparatus to bring thecomponent parts together in a coordinated assembly, each of theseaspects being believed novel as defined by the claims herein.

SUMMARY STATEMENT The method and apparatus of this invention utilizesthe stapling technique to fuller advantage by coupling it with aspecially-designed cone coil so that each coil is securely anchored andpositioned by a single staple.

For the purposes of the technique and the apparatus hereinafterdescribed, this special form of coil may be differentiated from othersnow in common use in that, at its small end, the final convolutionterminates in a chordal element which extends across the end convolutionapproximately diametrically thereof. Thischordal element or cross bar atthe small end of the coil becomes not only the means for positioningandanchoring the coil on the wooden slat frame, but is also the means bywhich the'coil is supported in the assembly apparatus, as well as thereference for orienting the spring coils rotatively so as to positionproperly the knots at their large ends for later assembly of thesupporting face of. the box spring construction.

To summarize the assembly technique as briefly as possible, theabove-described coil is placed over the nose of a stapling gun, themuzzle of which has been modified to receive the aforementioned crossbar at the small end of the cone coil in such manner that the staplewhen driven will encircle that bar approximately midway thereof. Inorder to eliminate extraneous holding means for maintaining thisrelationship of spring coil and stapling gun for the stapling operation,the stapling is preferably performed with the stapling gun pointedupwardly so that gravity holds the coil in place. The obvious corollaryis that the flat frame of the box spring is inverted and overhead, theassembly being made in the upside-down condition, the stapling gun withcoil thereon being moved vertically upwardly with respect to the slatframe to position the coil thereon for stapling. The gun is then firedwith sufficient force not only to drive the staple securely into thewood and into encircling engagement with the cross bar of the spring,but also to impress or to indent the cross bar itself firmly into thewood. a

The apparatus for carrying out the method includes thevertically-positioned upwardly-directed stapling guns in ganged orbanked array suitable for stapling at least one row of springs at a timeto the base frame. The guns are mounted on a movable carriage which ismoved by power from a lower loading position to an upper firingposition, and the stapling guns are suitably powered from a commonsource and fired simultaneously by a common trigger control. Theinverted slat frame moves in suitable overhead ways, and is bucked by asuitable backing arrangement at the stapling station, to which and fromwhich each cross slat of the base frame is indexed in turn to receive arow of coils.

These successive operations are organized into a selfterminating cycleby means of a suitable programming controller such that the operator,after having charged each operative gun with a spring coil, manuallyinitiates the cycle which is thereafter self-executing, and at the endof which the guns are returned to the loading station, ready to becharged with another row of coils for the commencement of yet anothercycle.

While I have found it desirable from the standpoint of simpleexplanation of the several steps of the method and features of theapparatus to speak of hand loading the coils on the guns, I alsocontemplate the charging of the guns by machine as well, using a feedingapparatus of the kind disclosed in my Pat. No. 3,l93,l36 for presentingthe inverted spring coils one at a time from a nested stack of the same,to be picked up by the stapling gun passing axially upwardly through thespring coil at such feeding station.

THE DRAWINGS The invention is described in detail in connection with theaccompanying drawings in which:

FIG. I is a fragmentary perspective view of a box spring constructionpartially completed in accordance with the invention, showing the springassembly at one corner of the box spring frame;

FIG. 2 is a side elevational view of the basic elements of the assemblyapparatus, illustrating the sequence of operations by means of which thespring coil is carried by the stapling gun upwardly to the slat frameand stapled thereto;

FIG. 3 is a side elevational view of the overall apparatus showing asupply stack or magazine of the slat frames on the right, uppermost oneof which is on the ways and in the position at which its leading crossslat FIG. 7 is an enlarged fragmentary end elevational view of theindexing mechanism seen from the exiting end of the apparatus, i.e., theleft hand end as illustrated in FIG. 3;

FIG. 8a is an enlarged fragmentary elevational view of a portion ofthe'indexing mechanism, showing in particular the mechanism for ejectinga completed assemy;

FIG. 8b is an enlarged fragmentary view of the indcxing apparatusshowing the controller for the frame ejector of FIG. 8a; and

' FIG. 9 is a diagram of the electrical circuit and controller by meansof which the aforementioned individual operations are coordinated in anoperating cycle.

The Spring Coil Proper The spring coil is best seen in FIG. 1. It is asomewhat modified cone coil in that its five and one-half awaits a rowof springs at the stapling station at the far guns ready for firing,i.e., with the spring coils elevated into contact with the cross slat ofthe wood frame, and the overhead backing bars cammed into solid bucklingor shock-receiving contact with the upper side of the slat;

FIG. 5 is a fragmentary perspective view of the stapling mechanism asseen from the operators station, showing in greater detail the gun andits mounting, and the elevating and triggering mechanisms;

FIG. 6a, FIG. 6b, and FIG. 60 are each enlarged, fragmentary sectionalelevational views of the frame feeding or'indexing mechanism, shown inthe upper lefthand portion of FIG. 3, for positioning each successivecross slat of the box'frame at the stapling station, FIG. 6a showing theend or leading cross slat positioned to receive its coils, FIG. 6bshowing the slat frame in transit as the second cross slat of the frameis moved into the stapling station, and FIG. 60 illustrating the secondcross slat at the stapling station, and illustrating as well how eachsucceeding cross slat of the frame is thereafter so positioned;

convolutions do not decrease in diameter linearly but rather abruptlyfrom the major diameter of the upper knotted convolution 22 to the mainbody of the coil, which is of substantially smaller and so nearlyuniform diameter as to be almost cylindrical in appearance as comparedwith the usual cone coil. To those familiar with the spring art, it isapparent that this kind of coil exhibits a fairly abrupt change in loadcarry from an initial softness to a considerable stiffness as the firstor closed convolution deflects sufficiently to bring the succeedingconvolution of smaller diameter into contact with the load to besupported.

At its unknotted bottom end 24, the wire of the spring coil terminatesin a chordal element or cross bar 26 which is approximately the lengthof the minor diameter of the coil and is positioned approximatelydiametrically of the bottom convolution. This chordal cross bar serves anumber of purposes, not only in the construction of the box springitself but also in the handling and the orientation of the coil by theassembly apparatus.

As will be seen in FIG. 1, the cross bar 26 at the bottom of the coil isat or near the central axis of the coil, and also lies in the plane thatintercepts the knot 28 at the top convolution. Inasmuch as the locationof the knot at the top of the coil can be important to the particularone of many available methods for joining the individual coils togetherat their upper ends, the desired final position of the knot 28 mayeasily be derived from the bottom cross bar 26 as a reference, inasmuchas the muzzle of the stapling gun, as will hereinafter be pointed out indetail, is adapted to receive the spring coil in only one of twoalternate positions displaced I degrees from one another.

Therefore, when the spring coil, as is indicated in FIG. 1, is made sothat the cross bar 26 and the knot 28 share a common plane with thecentral axis of the coil, and when, as later will be described, themuzzles of the guns are arranged to receive the cross bars of the coilsto position them only crosswise of the cross slat 30 of the slat frame32, it is apparent that the position of the knot 28 at the upper end ofthe coil must be either on one side or the other of the cross slat 30or, stated with reference to the direction of movement of the slat frame32 through the apparatus, must either be fore or aft, i.e., on theleading or trailing edge of the spring.

I have found such orientation preferable to a number of kinds of topface assembly of the box-spring construction, and as a matter ofpractice, all of the springs .of all but the last row are usuallypositioned with their knots trailing with respect to the direction ofadvancement through the assembly machine, the knots of the last row ofsprings being presented with knots leading, so that each of theperipheral springs presents a smooth unknotted edge of the topconvolution for tangential connection to an encircling border wire orframe (not shown).

it is equally conceivable, however, that for some form of top-faceassembly of the construction, an orientation of the spring coil toposition its knots other than precisely leading or precisely trailingmay be preferred, in which event some other relative rotativedisplacement of the cross bar 26 at the bottom end of the coil and theknot 23 at the upper end of the coil may be preferred. In any case,however, the chordal cross bar 26 at the bottom of the coil serves asthe reference from which the coil is positioned.

As will be noted from FIGS. ii and 2., as well as other views, the slatframe 32 comprises the leading end slat 30, narrower intermediate crossslats 3i, and a trailing end slat 33(FIG. 8b only). These are nailed tolongitudinal side rails 36, the ends slats 36 and 33 each having asecond layer 36a and 33a in a common plane with the side rails 36. Inframes of greater width than the twin size frame shown, a center railwould be also be provided.

The individual stapling guns 35 ganged for unison operation in theassembly apparatus (FIGS- 4a and 4b), are powered by air, as isconventional with commercial industrial staplers, and are arranged, aswill be apparent from FIG. 4a, in a line abreast upon a verticallyreciprocable carriage 36 which itself is powered to travel between aretracted, lower, coil-loading position, shown in FIG. 4a, and an upperor firing position, illustrated in FIG. db. A particularly uniquefeature of the gun itself is that its muzzle is equipped with asurrounding sleeve 38 which is preferably of a slippery material such asNylon, Teflon, or the like, is generally cylindrical in shape and of adiameter slightly less than the minor diameter of the cone coil, and ischamfered or cone shaped at its upper end to facilitate the emplacementof the inverted cone coil thereupon.

The small upper end of the sleeve. 38 is provided with a diametricalhalf-round groove 66 in which the aforementioned crossbar 216 of theminor end of the coil is seated. It will be apparent, then, that whenthe bank of guns is in the loading position of FIG. 4a, each gun isadapted tp receive over its muzzle sleeve 38 one inverted coil springwhichmay be positioned in one of two positions at the discretion of theoperator, i.e., with the knots in one of two available positionsdisplaced 180 from one another. It will further be apparent that if someorientation other than a trailing or leading position of the knots weredesired, the same may be as well achieved by maintaining the samerelative orientation of knot 26 and cross bar 26 as is illustrated inFIG. l, but changing the orientation of the grooved seat 46 in themuzzle sleeve 38 of the stapling gun. Such change would necessarily belimited to such rotative displacement of the grooved seat 40 as wouldcontinue to insure that thestaple would straddle the cross bar 26.

In any event, the combination of the cross bar 26 at the bottom or smallend of the spring coil and the dia metrical seat 60 on the muzzle sleeve33 of the gun serve to determine the rotative displacement ororientation of the coil, and to maintain that orientation while thecoils rise from the loading position of FIG. 6a to the firing positionof FIG. 4b.

The sequence of these several operations is indicated more or lessdiagrammatically in FIG. 2. In FIG. :2, the inverted slat frame 32 isshown positioned for the connection thereto of the second row of springcoils, a first row having previously been stapled to the end or lead ingcross slat 30 of the slat frame. As earlier indicated, the gun 35 inlowered position corresponding to that of FIG. 6a is loaded with aspring coil 20 which is then elevated by upward movement of the gun tothe broken line position of FIG. 2 at which the bottom convolution andthe cross bar 26 of the spring are pressed firmly into contact with thesecond cross slat 31 of the base frame, and the upper or opposite sideof that cross slat is firmly bucked by a backing bar 42 which serves asan anvil on the cross beam Ml against which to drive the staple into theslat.

The firing of the stapling gun 35 is preferably done with forcesufficient to impress or to indent the cross bar 26 at the bottom end ofthe spring into the surface of the cross slats of the frame, the impactof this force being sufficient also to cause a slight bending of thecross bar in a vertical plane (See FIG. 1). The legs 46 of the staples48 are preferably chisel-shaped so as to be bent into a curvedconfiguration upon entering the wood, thereby to prevent theirunintentional dislodgement, and to anchor the springs 26 securely inplace.

The stapling accomplished, the guns are withdrawn, leaving their springcoils secured to the frame.

As will be apparent from FIG. 2, as well as from FIGS. 3 and 4, thestapling is performed with the springs 20 and the slat frame32 in anupside-down condition, thus to use the force of gravity to maintain thedesired orientation of the individual coil springs with the muzzles 38of the stapling guns.

Elevating and Firing the Stapling Guns The stapling mechanism,illustrated to the far left of FIG; 3 as well as in FIGS. 4a and 4b and5, is carried on a stationary frame, which comprises a pair of spacedstandards 50 which are weldments of steel plate connected together attheir upper ends by the cross beam 44, which is of inverted T section,and at their lower ends by cross bracing 52 of any suitableconfiguration. Above the lower cross brace, the standards are alsojoined by a tubular manifold 54, which is connected to a source ofpressure air, and to which the individual stapling guns 35 are connectedby suitable flexible hoses 56, (FIG. 5) the manifold chamber having avolume sufficient to ensurethat the guns will be powered uniforrnly.

The guns themselves are mounted upon the recipro cable carriage 36 whichincludes a pair of slide members 58, one at each end of the carriage,connected by a cross beam 60 upon which the stapling guns are firmlyclamped at uniform height in bolted pillow blocks 62. Each slide member58 is movable upon a vertical slide shaft 64 or way which is secured inbrackets 65 affixed to the adjacent standard of the frame. Each slide 58is provided on the slide opposite the operators position which a rack 66fixed thereon, and each rack is engaged with'a pinion 68 secured to across shaft 70 extending between, and journaled in bearings in, theopposed standards 50 of the stationary frame. One end of the shaft 70,as seen in FIG. 3 and at the left hand side of FIG. 4a, is provided witha driven pinion 72 which is in turn engaged by a reciprocable rack 74connected to the piston rod of a double-acting air cylinder 76, the rack74 being back on its side opposite its teeth by a roller 77 to take theside thrust of the toothed engagement.

As will be seen by comparing FIGS. 3, 4 and 5, the extension of the rack74 by the driving cylinder 76 rotates the shaft 70, which, through thepair of gears 68 engaged with the racks 66 fixed to the slides 58 of thegun carriage, causes the guns 35 thereon to move upwardly to theposition of FIG. 4b to carry the springs 20 into contact with the crossslats of the slat frame 32.

The guns are connected for unison firing by a common triggering bar 78which is carried by and therefore moves with the gun carriage 36. Thebar 78 is a square tube eccentrically mounted at its ends in bearings 79on the slide members 58 so that when rocked, one of its corner edgesengages the trigger 80 of each gun and causes the guns to tire inunison. The trigger bar is rotated by means of a double-acting aircylinder 81 mounted upon the carriage 36, and connected to a crank 82 onthe trigger bar, causing the bar to rock when the piston of the firingcylinder is moved.

Bucking The Slat Frame While Stapling As may be appreciated from FIGS. 1and 2, the inverted slat frame 32 is not of itself equipped to resistunyieldingly theimpact of the staple because, when the guns are elevatedto emplace the inverted coils against the downward face of the invertedslat, the thenupward surface of the slat would be out of contact withthe upper cross beam 44, and would be supported firmly only under thelongitudinal side rails 34 (and center rail when present) of the baseframe. (See FIG. 4, 7 It is, accordingly, desirable to transmit the firmsupport of the upper cross beam 44 directly to the cross slats inorderto buck the same when the guns 35 are fired.

The backing bar'42 for bucking the cross slats, and the operatingmechanism therefor, are best shown in FIGS. 4a and 4b, and in FIGS. 6aand 6c. The backing bars 42 are two in number, one on either side of thecentral feeding or indexing mechanism 83 by means of which the slatframe 32 is advanced through the apparatus. Each backing bar 42 ispositioned in a slot 84 (FIG. a) in the flange of the inverted crossbeam 4, and by means of lugs 86 is reciprocably mounted upon a pair ofcapped posts 88 each screwed into the upper side of the girder flange.The backing bars 42 are normally maintained in an upper or retractedposition on the cross beam 44 by means of compression springs 90 whichencircle the posts 88. When retracted, the lower edges of the bars 42provide ample clearance for the passage therebeneath of the cross slatsof the slat frame 32 as the same are being advanced by the indexingmechanism 83 with the ends of the cross slats 30 resting upon theangle-iron frame ways 92 seen in section in FIGS. 4a and 4 b, and inside elevation in FIG. 2 and in the several FIGS. 6.

To bring the backingbars 42 into supporting contact with the uppersurface of a cross slat to resist the driving force of the staple, fourcam levers 94, two for each backing bar, are ganged to a connecting rod96 which in turn is pivotally connected to the clevis of the piston rodof a double-acting air cylinder 98 mounted at one end of the upper crossbeam 44. As will quickly be seen frames is employed. I

from comparison of FIGS. 4a and 4b (also 6a and 6c), the extension ofthe piston rod of the cylinder causes the connecting rod 96 to move fromleft to right, as there seen, rotating the several cam levers 94clockwise to cam the backing bars 42 downwardly into bucking contactwith the cross slat of the frame.

The drive cylinder 98 for the backing bars 42 is connected to theoperating valve that controls the drive cylinder 76 for elevating thegun carriage, so that pressure air is admitted to both simultaneously.However, inasmuch as the cylinder 98 issmaller in diameter as well asstroke, it completes its movement before the guns are fully elevated,assuring that the cross slat ,is solidly backed for the arrivalof theguns and therefore solidly bucked for their firing.

Because the apparatus is adapted to be employed for the manufacture ofbox springs that vary in width, i.e., to accommodate at least thestandard twin and doublebed widths, as well as others, the ways 92 uponwhich the slat frame 32 advances through the apparatus are adjustablymounted upon the flange of the cross beam 44, being suspended therefromon brackets 100 that are adjustably clamped to the flange by means ofset screws (FIG. 2). Similarly, to accommodate the narrower widths ofthe twin-size frame, the backing bar 42 is made adjustable in length byproviding it with seg-. mental engaging elements or shoes 102, which areattached to the reciprocable backing bar 42 by means of screws and whichpermit the convenient removal of a sizeable portion of the engagingedges of the bars to accommodate the twin size frame, or the completereplacement and substitution of different shoes in the event that otherwidths or slats arrangement of base In a similar manner, the positionsof the guns on the movable gun 36 can likewise be adjusted to controlthe intercoil spacing, as may be desired to accommodate other than themajor sizes of box springs which will occupy the greater portion of theoperating time of the apparatus.

Feeding the Slat Frame to the Stapling Station As is indicated generallyin FIG. 3, a stack or magazine 103 of prefabricated slat frames 32 issupported upon a scissors elevator 104 which is operated on call byhydraulic power to elevate the stack of frames one frame thickness at atime to bring a new frame to the level of the frame ways 92 and into theoperating range of the feed pawls of the indexing mechanism 83 after thepreceding frame has advanced sufficiently to clear the leading edge ofthe stack. The stack elevator 104 is operated automatically by controlmeans yet to be described.

The frame ways 92 extend from the magazine 103 to the stapling station,being supported at their rearward ends, adjacent the feed stack, by anupright frame comprising a pair of side columns 106 connected at theirupper ends by upper cross beams 107 and 108, and a lower cross beam 109.

Upper cross beam 108 and lwoer cross beam 109 are connected by numerousvertical filler rails (not shown) which constitute an abutment againstwhich to emplace the stack 13 of slat frames, whose side edges areguided by posts 110 on the frame elevator 104. They also support thecontrol box 111.

The entering ends of the frame ways 92 are supported on a slide shaft112 secured in brackets near the upper ends of the columns I06, theconnections of each way to the shaft 112 being made by a bracket (notshown) that is secured to the way and adjustably locked in place on theslide shaft I112 by a set screw.

- As shown in FIG. 3, the frame ways 92 extend forwardly to the frontedge of the stapling mechanism support standards 50 from which point theinverted slat frame, after having received its coils, is transferred toextension ways (FIG. 8d only) from which to be removed in any convenientmanner for future operations.

The indexing mechanism 83 is the most complicated part of the apparatusand is shown in FIGS. 3., 41, the several FIGS. 6, and also in bothFIGS. 8.

It consists essentially of double-acting double-ended air cylinder I14whose reciprocable piston rod H6 is suitably extended and fitted withthree depending feed dogs or pawls I18, I20 and I22, of which the pawlII8 is normally inoperative, being called into operation only once foreach frame to eject the frame from the apparatus upon the completion ofthe stapling of a row of coils on the last cross slat 33 of the frame.

As illustrated in FIG. 3, the drive cylinder II I- is mounted on theback side of cross beam 44 of the stapling mechanism, i.e., on theexiting side of the stapling station. At the rearward end of the pistonrod II6 of the drive cylinder I14 there is fitted a bracket I24 fromwhich the intermediate feed pawl I20 is suspended, and which also servesas a coupling for an extension rod I26 at the extreme rearward end ofwhich there is similarly mounted a corresponding bracket I23 from whichthe rearward feed pawl I22 is suspended. The extension rod I26 issupported in a slide bearing 1107((1) in the upper cross beam I07.

At a suitable time in the operating cycle the valve controlling theoperation of the drive cylinder II4 is energized by the automaticcontroller, causing the piston rod I16 to be extended to its retractedposition shown in FIG. 3, and then almost immediately, as in acontinuous operation, to move forwardly causing the intermediatefeedpawl I20 to engage a cross slat of the slat frame then on the ways, andto move that cross slat forwardly to the stapling station. At the sametime, the rearward feed pawl I22 either assists in that feeding actionduring the time when both pawls are operative upon a single frame, or attimes causes the rearward feed pawl I22 to engage a cross slat of thenext frame of the magazine I03 to move it onto the frame ways 92.

The intermediate and rearward feed pawls I20 and I22 are simply barspivoted on a horizontal axis in their respective mounting brackets,chamfered at their front edges to match the generally vertical rearwardedges of the cross slats of the slat frame 32, and urged by gravity tothe operative position at which they are stopped by the engagement oftheir rearward ends with an abutting surface of their mounting brackets.Thus, on the rearward stroke of the rod of the cylinder M4}, the feedpawls I20 and I22 ride freely over the next rearward cross slat of theframe, falling into position poised for the next feed movement (Seedotted line position FIG. 60).

That portion of the indexing mechanism which serves to position thecross slat accurately for the receipt of a row of coils is shown indetail in the several FIGS. 6. In FIG. 6a, the leading cross slat 3d ofthe frame, which is wider than all of the intermediate cross slats 3I ofthe frame, is positioned at the stapling station to receive its row ofcoils. The feed pawl I20, under the driving force of the air cylinderII4, has moved the leading edge of the slat frame firmly against a pairof positioning stops I30, each adjustably secured to one of two rockshafts I32 journalled in hearings on the upper side of the flange of thecross beam M. The rock shafts I32 are also shown in FIG. 7 which alsoillustrates the torsion springs IM by means of which the rock shafts arenormally biased to lift the stops I30 outof the frameengaging position(FIG. 6b). The rock shafts flank the indexing cylinder I44, and each isrocked by its own separate crank 136 engaged by the cam end of a pushrod I38. The pair of push rods I38 flank the piston rod II6 of thecylinder I14, and extend through slide bearings in the web of theT-shaped cross girder M to bearing blocks I40 secured to sides of acentral channel member I42 cantilevered rearwardly from the web of thecross girder &4. The push rods I38 are positioned so that theirchamfered or cammed front ends are poised to contact the roller of therock-shaft crank I36 when the feed mechanism is in the retractedposition. On each push rod I38 there is pinned a push block I44 which isnormally engaged with the front face of the bearing block Mil, beingurged into contact therewith by a compression spring I46 surrounding thepush rod between the push block I44 and the web of the cross girder 44(FIG. 6b). In that position, the cam end of the push rod is fullyretracted and the rock shaft I32 ro tated by the torsion springs toremove the stop I30 from the path of the slat frame 32.

To place the stop in operative position, the push rods I38 are advancedto the position of FIGS. 6a and 6c, the cam ends of the rods turning thecranks I36 to rotate the stop I30 to its depending position at which tointercept the leading edge of the frame 32. The push rods 138 areadvanced by cross pins M8 extending sidewardly from the bracket. I24which on the fully retracted stroke of the piston rod I116, ispositioned well to the rear of the push blocks M4. The push blocks I44are in sliding contact with the sides of the support channel I412 toprevent the turning of the rod I33 on its own axis while it reciprocates(Compare FIG. 4i and ti).

Thus on the return or working stroke of the piston IId the advancingfeed pawl bracket I24 thrusts the push rods I38 forwardly to move thereciprocable frame stops 13f) from the position of FIG. 6b to theposition of FIG. 6a, thus to form an abutment against which the feedpawl 12% positions the leading cross slat of the base frame.

The frame stops 130 are actuated on every feed stroke of the machine,but as it depends from the rock sahft only sufficiently to engage theupper layer 30a of only the leading cross slat, it is in factinoperative and of no consequence during the indexing of subsequentcross slats 3i and 33 of the frame.

From FIG. 6b it will be apparent that the frame stop I30 is in the stopposition only during the last portion of the feed stroke of the indexingmechanisminas much, as there is a considerable amount of loss motion ofthe feed pawl bracket 124 before the push blocks M4 are engaged by thecross pins 148 (See FIG. 6b). This loss motion permits the trailing slat33 of the base frame (which is also of double thickness) to clear thestapling station before the frame stop I30 is again de- For the secondand all succeeding cross slats of an individual base frame, the upperframe stop 130, as earlier indicated, is ineffective, and a second framestop 150 is therefore provided, insertable through a notch or slot 152through the supporting flange of the frame ways 92 from the under sidethereof at the appropriate time to intercept the forward edge of thesecond and all succeeding cross slats of the frame. Its operation isillustrated in each of FIGS. 6a, 6b and 6c, which together show not onlyhow the lower frame stop 150 serves its function, but also how it isselectively disabled for the passage of the leading cross slat 30 of theslat frame.

The lower frame stop 150 is shown in operative position in FIG. 6cengaged with the forward edge of the second cross slat 31 which isfirmly seated against it by the intermediate feed pawl 120 of theindexing mechanism. The lower frame stop is essentially hook-shaped andpivotally mounted on the underside of the frame way 92 to be rocked by acrank 154 into and out of frame-engaging position under the influence ofan air cylinder 156 mounted on a bracket 157 secured to the way 92. Thestop-actuating cylinder 156 is singleacting, having a self-containerspring (not shown) which tends to extend the piston rod so as to retractor withdraw the lower frame stop from engaging position. The cylinder isoperated by a solenoid valve under the influence of a normally openswitch 158 which is mounted on the support channel 142 and positioned tobe operated by a cam bar 160 on the upper surface of the mountingbracket 124 of the intermediate feed pawl 120. Under normal conditions,therefore, when the mounting bracket 124 for the intermediate feed pawl120 has advanced sufficiently to cause its upper cam bar 160 to depressthe plunger of the control switch 158 of the frame-stop actuatingcylinder, the frame stop 150 rises into the frame ways to intercept theoncoming cross slat 31 of the base frame. Conversely, as the feed pawl120 retracts for another indexing movement, the switch 158 is openedbefore the end of the retraction stroke (dotted line position FIG. 6c)and the lower frame stop 150 drops away to the position shown in FIG. 6bwhich it maintains until, on the subsequent feed stroke, the cam bar1611 again actuates the switch to apply air to the cylinder 156 and toelevate the lower frame stop 150 into engaging position.

In order to disable the lower frame stop 150 for the positioning of theleading cross slat 31), which is too wide to be serviced by the lowerstop, a second and normally-closed switch 162 is mounted on the upperside of the flange of the cross girder 44 with its operator positionedto be intercepted by the upper portion 30a of the leading cross slat ofthe frame. That switch is in series with the normally-open switch 158.When that switch is operated as indicated in FIG. 6a, the switch 162 isopened, rendering it impossible to close the control circuit to thevalve controlling the lower frame stop 150. Therefore, as long as theswitch 162 indicates the presence of the leading cross slat 31), thelower frame stops 1'50 remain inoperative, and the leading edge of theframe advances to the upper stop 130.

Again, since the trailing cross slat 33 is the mirror image of theleading slat 30, i.e., with the upper thickness thereof disposed at theright-hand side or trailing edge of the last cross slat, it is not in'aposition to actuate the switch 162 before the leading edge of thetrailing slat contacts the lower stop 150, and therefore is of no effectin disabling the lower frame stop 150 for the interception of the lastor trailing cross slat 33 of the frame.

Elevating the Frame Stack and Spacing the Frames It will be apparentfrom FIG. 3 that as approximately one-half of a slat frame has advancedthrough the stapling station, the trailing edge of the frame will clearthe supply stack 103. While the uppermost frame is on the ways intransit to the stapling station, one of its longitudinal side rails isfollowed on its then upper surface by the depending operators of a pairof sensing switches 164 and 166 which are mounted on a bracket 168secured to the frame way 92, and spaced longitudinally of the directionof travel of the slat frame through the apparatus, the rearward switch166 being disposed above the leading edge of the stack of frames 103,and the forward switch 164 being positioned forwardly thereof above theframe ways.

Both the sensing switches 164 and 166 are of the normally closed type,and are wired in series with the elevator motor starter so that theclosing of both is re quired to call the elevator into operation. Thus,when the slat frame in the frame ways in the stapling apparatus clearsthe forward switch 164, a circuit is finally completed through bothswitches, and the stack begins to rise until the rearward switch 166 isonce more operated to open the circuit. The uppermost frame of the stackis then at the level of the frame ways 92, and on the next indexingmovement opens the forward switch 164 as well.

It will be apparent from the foregoing that the spacing of the twosensing switches 164 and 166 controls the spacing between successiveslat frames, which is set at a distance slightly in excess of the normalinterslat spacing so as to allow for the greater width of the leadingslats of the frame. As the increment of movement is the length of thefeed stroke of the indexing mechanism, it will ne apparent that theinterframe spacing will be the length of the feed stroke or. somemultiple thereof, determined by the placement of the forward switch 164along the frame way. One feed stroke is sufficient for the purpose,which is in part to permit the intermediate feed pawl to drop intoposition behind the last or trailing cross slat 33 of the frame so as tothrust it forwardly to the stapling station. It will be apparent at thesame time that this necessary gap between successive frames establishesthe need for one indexing movement that is not accompanied by the othersteps of the normal operating cycle. this purpose the electrical controlmechanism is arranged for manual operation of each of the functionsseparately, so that the operator by actuating the necessary switch, caneffect one independent indexing movement, advancing the leading slat ofthe succeeding frame into the stapling station.

It is similarly necessary to preserve the interframe spacing at thestapling station for the discharge of the completed frame and thearrival of the succeeding frame in order to provide clearance for thelowering of the upper frame stop 130, i.e., because of the necessity ofinserting the stop after the completed frame clears the station, andbefore the succeeding frame arrives, it is not possible to utilize thesucceeding frame to push the completed frame on its way. A separateejector mechanism is therefore provided at the exiting end of theapparatus.

Ejecting the Completed Assembly The ejector pawl 118, as will be seen inFIG. 3, is a forward extension of the indexing mechanism 83. Togetherwith its controller, it is shown in greater detail in FIG. 8, the pawl118 also being seen in end view in FIG. 7.

Whereas the intermediate feed pawl 1211 and the rear feed pawl 122 areurged by gravity to a depending operative position, always eitherengaged with or poised for engagement with a frame cross slat exceptduring the retracting stroke, on which those slats are overriden, theforward ejector pawl 118 is normally inoperative, being lifted andmaintained out of frame engaging position by a small single-acting aircylinder 170. The pawl itself is pivotally suspended from a bracket 172affixed to the forward end of the piston rod 116, and by its unbalancedweight is urged to the broken line frame engaging position of FIG. 8a.It is alsourged into that position by a return spring (not shown) whichis within and part of the air cylinder 1711 which is mountedton theforward face of the pawl bracket 172 and has attached to its downwardlyextending piston rod a lifting arm 17 1 which is pivotally connected tothe pawl 118 by a pin-and-slot connection 176 within a recess 178 milledin the pawl forwardly of its main pivotal mounting. When the aircylinder 1711 is energized, therefore, the ejector pawl 118 is liftedand maintained in its elevated position, where it remains idlethroughout the normal operation of the indexing mechanism, air beingconstantly supplied to the cylinder 171) except when the last ortrailing cross slat 33 of the frame is positioned at the staplingstation (and fleetingly and ineffectively during the arrival of theleading cross slat 31) at the stapling station).

The control of the forward ejector pawl 118 is effected by a small airvalve 188 through which pressure air is normally applied to the cylinder170.. The valve is mounted on a bracket 18?; screwed to the flange ofthe cross beam' ld and positioned so that its operating leaf 18 1 willbe lifted by the upper layer 330 of the trailing cross slat 33 when thelatter is positioned at the stapling station. When the valve is operatedby lifting the operating leaf 1841 the connection to the pressure sourceis interrupted and the cylinder is vented to atmosphere through thevalve body. Thus, when the operating leaf is lifted to the dotted lineposition shown in FIG. 8b, the feed pawl 118 is correspondinglydepressed to the broken-line, slat-engaging position of FIG. 8a, andremains so poised for the indexing movement that completes the laststapling cycle for a given frame. On the retraction stroke, the pawl 118overrides and falls behind one of the intermediate cross slats 31 of thecompleted frame, and on the forward stroke removes it from the staplingstation.

Inasmuch as the upper layer 33a of the last cross slat 33 is in engagingcontact with the valve-operating leaf 181 for a distance less than thelength of the indexing stroke, pressure air is re-admitted to the aircylinder before. the ejection stroke of the forward feed pawl 118 iscompleted. Thus, to maintain the engagement of the ejector pawl 118 withthe frame, the former is provided with a forwardly extending lower lip18@ which maintains the engagement of the ejector pawl with the crossslat with the completed frame throughout the ejection stroke. If theextension ways 188 (FIG. 8a only) are clear, the forward momentum of thecompleted frame will disengage the cross slat from the ejector pawl,permitting the air cylinder to raise it to the full line position of theFIG. 8a. However, if an accumulation of completed frames in theextension ways should not permit disengagement in that manner, it willoccur at the beginning of the next retraction stroke of the indexingmechanism, the lifting force of the cylinder being inadequate to damagethe mechanism.

Inasmuch as the valve is operated by the passage thereunder of the upperlayer 33a of the trailing slat 33, it will be apparent that it issimilarly lifted by the upper layer 311a of the leading slat 30, butonly momentarily as will be apparent from comparison of FIG. 6a, whichillustrates the leading cross slat at the stapling station, with FIG.8b, which shows the trailing cross slat similarly so positioned. Thus,the ejector pawl 118 is momentarily but idly positioned in thebroken-line position of FIG. 8a as the intermediate feed pawl 120 movesthe leading cross slat 31) into the stapling station.

Electrically Controlling the Cyclic Operation Central to the operationof the: circuit is a motordriven industrial timer 111, the elements ofwhich are enclosed within the broken line of FIG. 9. They include atiming shaft driven by a motor 191 which is placed into operation by aninitiating manual switch 192 which is preferably a pedal-operated switchat the operators position in front of the stapling station, and aholding switch 194 operated by :a cam on the motordriven shaft. Theholdingswitch continues to apply power to the driving motor when theinitiating manual switch 192 is released, holding the motor in foressentially one revolution of the shaft after which the holding switch194 opens, de-energizes the motor, and thus determines the length of anoperating cycle.

On the same shaft 190 are three other cam-operated switches 196, 197,and 198 controlling respectively the solenoid valves 200, 201, and 211 2which control respectively the air cylinder 76 which elevates the guncarriage, and with it the air cylinder 98 which depresses the backingbars, the latter two being controlled in common by the valve 200, theair cylinder 81 which rocks the trigger bar to fire the guns, and theair cylinder 114 that powers the indexing mechanism 83. The cam-operatedor timing switches 196, 197 and 198 are each connected to theirrespective controlled solenoid valves through one of threemanually-operated threepole switches 203, 2114 and 205 the lowercontacts of which must be closed to render the automatic control leroperative. A fourth manually-operated three-pole switch 206 servesessentially to condition the slat frame magazine 1113 for automaticoperation.

It will be apparent from the diagram that the timing motor 191 isconnected to power through the lower set of contacts of each of theaforementioned manuallyoperated three-pole switches 203 to 2116,inclusive, requiring that all such contacts be closed before the timingmotor may be energized, and also that the circuit to the timing motor isinterrupted if any of those contacts should be opened. A third set ofcontacts of each of the four triple-pole switches 203, 204 and 205operate signal lamps 207, 208, 2119 and 210 to indicate that the timerswitches 196, 197 and 198, the elevator 104, and the timer motor 191 areconditioned for operation.

it will be apparent then that when the cycle-initiating switch 192 ismanually closed by the operator after he has closed each of theaforementioned four triple-pole switches 203 to 206 inclusive, the timershaft 190 com mences to turn causing, successively, the guns 35 toelevate as the backing bar 42 comes down, the trigger bar 78 to rock andto fire the guns, the guns to retract, and the slat frame 32 to index inpreparedness for the beginning of the next cycle. Each of the aircylinders 76, 98, 81 and 114 controlling these four basic movements is adouble-acting cylinder and, accordingly, the solenoid valve whichcontrols each is a two-position springreturn valve which normallyapplies pressure air to one side of the operating piston while ventingthe other, but reverses that condition when the controlling timerswitches 196 to 198 are closed to power the valve solenoids.

The air cylinders 156 that operate the lower frame stops 150 are of thesingle acting type, as earlier mentioned, and spring-biased to retractthe lower frame stops from their frame engaging positions (FIG. 6b). Thevalve 212 which controls the cylinder 156 is itself controlled by theearlier-mentioned normally-closed switch 162 mounted on the uppersurface of the cross beam 44. These two switches, as shown in FIG. 9,are connected in series and when closed cause the admission of pressureair to the cylinder 156 to elevate the lower frame stop. As earlierpointed out, the normally open 158 switch is closed after the indexingstroke has proceeded sufficiently to permit the preceding cross slat toclear the stapling station, so that the lower stop 150 may resume itsposition without obstruction.

The two normally closed switches 164 and 166, which energize'the drivemotor of the hydraulic lift mechanism 104 of the frame magazine 103, areconnected in series to the drive motor through the same set of contactsof the switch 206 that light the signal lamp 210, the switch 206 thusinterlocking the elevator 104 with the timer motor 191. As earlierexplained, the removal of one slat frame from the top of the magazine103 permits the switch 166 to close, and when the trailing edge of thatframe has finally cleared the forward switch 164, the elevating motor isenergized, lifting the stack 103 until its uppermost frame again opensthe rearward switch 166. When the magazine is empty and the last framehas also cleared the forward switch 164 the elevator proceeds to itsmaximum height at which point, with the hydraulic ram fully extended,its pump bypasses until the operator shuts it off. This he does bymanually operating the triple pole switch 206, the middle contactor ofwhich is connected for double-throw operation, and applies power to asolenoid to open a valve 214 which vents the hydraulic lift cylinder toits sump permitting the elevator 104 to descend to be recharged with anew stack.

Each of the solenoid valves 200, 201 and 202 may likewise be operatedindividually by manual switches 216, 217, and 218 respectively, fortesting and maintenance.

The entire control circuit is connected to power through a double-polesingle throw switch 219, both lines to which are appropriately fused inaccordance with conventional practice.

Conclusion in the foregoing description, l have set forth what I believeto be a full disclosure of a new method of fabricating box springassemblies by the stapling technique made possible in part bymodification of the spring coil for assembly to the slat frame by a guninserted axially through the interior of the spring. With this springand by this gun it is possible to secure the cone coil to the box springframe by means of a single staple and, if adequate force be used indriving the staple, the spring can be locked against rotationaldislodgement by having its stapledpart impressed into the surface of thewood. This single staple connection is sufficient, after the top face ofthe spring assembly is united by whatever interlacing or joiningtechnique may be chosen, to maintain securely the connection of thesmaller bottom end of the spring coil to the wooden slat frame,

In the apparatus that l have provided for the practice of the method, Ihave found it advantageous to employ the weight of the individual coilsas the method of maintaining their orientation with the stapling gun andthus to perform the stapling with the stapling guns pointed upwardly,and with the springs and the slat frames upside down. The indexingmechanism by means of which the slat frame isfed to the staplingapparatus one slat at a time is such as to square the slat at thestapling station to assure that the springs are attached in a lineparallel to the slat edges, and, in the case of the intermediate slats,centrally thereof. This is accomplished, notwithstanding any slightlyskewed positioning of an individual cross slat, by feeding the framewith a feed pawl that-engages the slat at or near the center of itstrailing edge while positioning the slat with two widely spacedabutments or stops that engage the leading edge of the slat near itsends, and utilizing sufficient feeding force to assure tight ultimatecontact of the slat with all three.

The features of my improved coil, assembly method, and apparatusbelieved patentable are set forth in the appended claims.

What is claimed is:

l. A helical wire coil compression spring for box springs or the likecomprising a plurality of convolutions having a helical pitchsubstantially greater than the thickness of the wire, the endconvolutions thereof being substantially normal to the axis of the helixand one of them terminating in a wire portion extending as a chordacross the said one end convolution.

2. The spring of claim 1 in which the spring is discrete, the chordalportion extends substantially diametrically of the said end convolution,and the otherend is knotted to form a closed loop.

3. The spring of claim 2 in which the coil is coneshaped, the chordalportion is at the small end and substantially diametric in length aswell as orientation.

4. The spring of claim 2 in which the spring axis,

knot, and chordal portion are substantially co-planar. l= l

1. A helical wire coil compression spring for box springs or the likecomprising a plurality of convolutions having a helical pitchsubstantially greater than the thickness of the wire, the endconvolutions thereof being substantially normal to the axis of the helixand one of them terminating in a wire portion extending as a chordacross the said one end convolution.
 2. The spring of claim 1 in whichthe spring is discrete, the chordal portion extends substantiallydiametrically of the said end convolution, and the other end is knottedto form a closed loop.
 3. The spring of claim 2 in which the coil iscone-shaped, the chordal portion is at the small end and substantiallydiametric in length as well as orientation.
 4. The spring of claim 2 inwhich the spring axis, knot, and chordal portion are substantiallyco-planar.